Center of Mass (Human Body) Definiton?

[Oh Shoot]

In another thread, in reference to being shot in the gut, COM was mentioned...

I always took it to mean chest area, with dead center being sternum, right between the pecs.

TNRoboCop disagreed, "Center of mass for the human body is from the bottom of the neck where it meets the chest to the beltline."

so as I searched around some, I was surprised I couldn't really find a "definition" of what COM is, even looking at well known firearm trainers' works, FBI, etc.

No big deal, but curious, what do you consider COM? Especially interested in instructors' input, and/or those who have had more advanced training.

- OS

[Garufa]

While I don't have the requisite credentials as asked for in your query, an argument could be made for both the entire torso or the sternum area.

I personally consider it the sternum as you do. That would be the most effective area as I see it for shot-placement what with the bone and all.

[Guest rsgillmd]

The way center of mass is used in firearms classes is just another inappropriate use of a term that has a definition.

From Wikipedia: The center of mass or mass center is the mean location of all the mass in a system.

I was taught in EMS class and again in med. school that the center of mass of a human body is around the pelvis. Those claims are confirmed at the website below:

SparkNotes: SAT Physics: Center of Mass

Just like talk about the cranio-ocular region -- it's for convenience. Theoretically if you want a one shot stop, you need to take out the brainstem. If you look in any anatomy atlas, you will see the brainstem is most closely at the level of the maxilla (cheek bone). So ideally you should be aiming for the cheek bone, close to the nose (middle). But since in a true self defense situation you will not find someone who can aim with that precision, and because other nearby hits are likely to still be effective, a region has been created.

Since I got started on anatomical theory, I would argue that if you want to kill, you should really shoot for the sternal notch. With a well placed shot you'll take out trachea, and ascending aorta, and the vena cava before it even impacts the spinal column. If blood does not go out much, and does not return much, and you can't exchange air, you die. Why bother messing around with bullets bouncing off/getting slowed down by ribs?

However in a self defense situation our purpose is to stop the bad guy, not necessarily kill him/her. So the above is merely theoretical conjecture based on knowledge of anatomy.

Edited July 26, 2010 by rsgillmd
rewording

[Defender]

At one time I was an instructor in the USAF, and conducted firearms training for Air Force cops. Our concept of Center Mass, was not dictionary oriented, but more based on roughly the center of the torso, with the thought that even a hit slightly off target would still have a high likelihood of hitting the torso/vital organs, whereas a shot targeted to the head or extremity for example, that was slightly off target would miss altogether, and possibly hit an unintended target behind.

[JayC]

Center of mass is defined in the document below, along with why the "traditional" center of mass is not a perfect target... The entire goal behind shooting center of mass is to stop the attacker by causing serious damage to vital organs, as you can see the vital organs are only in the upper half of the traditional COM zone.

Terminal Ballistics

My recommendation is to train focusing fire on the upper part of COM (between the armpits) which will lead to better stopping than hits in the lower half of the traditional COM. (Truth be told any hit inside the COM is better than a complete miss... but I believe hits in the upper chest will tend to be more effective since those hits will be to the lungs and/or heart, while kidney's, liver, etc in the lower half may very well kill you, won't stop you as quickly.)

[Guest Jamie]

Well... the actual center mass of the human body - that point that it would balance on if it were ridged - varies. For a male that's not carrying an excess of body fat it would be right around their belly button. For a female, it would be a couple of inches lower than that due to their build and disposition of fat.

But as far as shooting at someone and getting them to stop, I'd call center mass the center of the main group of organs in their upper torso.

And since all the really important and bleedy stuff seems to be between a person's navel and the top of their sternum, I'll be aiming for the center of that particular mass of tissue... which to me looks to be about the tip of the sternum.

J.

[dunndw]

I'd agree with Jamie on the COM. Center mass is the neck, chest, belly area. Let me muddy it a bit more for you. The way I explain it in my classes is it's the center of whatever they present to you. If it's their torse, then the center of that, if it's their leg, the center of that as well.

[vontar]

Also, consider the COM from the angle you stand, say you are at an angle.

Twisting this a bit, say you are not in a straight on shot to the target, say you might be in defense of 3rd party. (lets not go down that road right or wrong, for this lets assume right)

You might be at an Odd angle to the target, so your shot would be at a COM that gives you the most likelihood of a hit.

COM could be defined as the Center of the target as to the aspect that is presented to your line of sight.

[Mike.357]

I always look at COM as where vital organs are. You may not hit the heart buit a shot in the kidneys or liver is gonna do someone in most likely. Lungs and they are not going to want to play anymore.

So to me basically the sternum and gut areas will suffice as a definition.

[TNRobocop]

As I stated in the other thread, in all of my training, military and LE, it was generally explained that the center of mass for the human body is from the bottom of the neck where it meets the chest to the beltline. Center of mass on the human body as a whole, not center of the chest.

Below that is the pelvic girdle region, which believe it or not is starting to gain popularity for an engagement area due to stopping mobility and large amounts of blood flow through it.

Above that is the head/throat area which unless engaged in the crainial vault area, is not usually a DRT shot.

[JAB]

No credentials to list but, just in my own mind, like Jamie, I think of COM with regard to SD target acquisition as being the xiphoid process. I figure if I am off even a few inches to the left, right, up or down I'm still hitting the assailant in the torso and, unless I am facing The Terminator, that's probably going to adjust their attitude and make them reconsider the (as Ayoob says) victim selection process whether it is a fatal shot or not.

[Guest Jamie]

As I stated in the other thread, in all of my training, military and LE, it was generally explained that the center of mass for the human body is from the bottom of the neck where it meets the chest to the beltline. Center of mass on the human body as a whole, not center of the chest.

I've not only had both military and police training, but about 20+ years of martial arts training, plus a fair amount of anatomical studies and training as well... and I can tell you that what you've outlined there is NOT the center mass of the human body as a whole. It's not even the the entire mass of the human torso, which consists of everything between the crotch and the top of the sternum.

Below that is the pelvic girdle region, which believe it or not is starting to gain popularity for an engagement area due to stopping mobility and large amounts of blood flow through it.

Yep, changing the structure so it no longer functions - destroying hip joints, for instance - will put a person on the ground quick. They'll still be able to shoot back though, 'til they bleed out, or they're overcome by either pain or shock.

Above that is the head/throat area which unless engaged in the crainial vault area, is not usually a DRT shot.

Maybe not if it's a near-miss, but if a person is squarely hit through any one of the 1st through 7th vertebrae, they'll hit the ground like a sack of . And if the hit is higher than about C-4, they won't even be able to lift a finger, much less continue an attack.

They may or may not die from the wound, but you can't get much more stopped than they'll be, short of dying. And it's possible that even a glancing blow on that portion of the spine may have that effect.

J.

[TNRobocop]

What I was referring to the center of mass for the body for "engagement" purposes, not a scientific purpose.

As far as vertebre go, most shots are not going to be from behind, but rather frontal/side/oblique type shots. Specifically sniper engagement zones, but would work for most firearm engagements also.

[Guest Jamie]

What I was referring to the center of mass for the body for "engagement" purposes, not a scientific purpose.

And for engagement purposes, a bullet that strikes a person between their navel and the top of their hip bones, that doesn't hit either the spine, or one of the two major arteries that parallel it, isn't going to hit much that will be instantly incapacitating.

The person may die within a week from the resulting infection, but they're likely to have plenty of fight left in 'em for a while before that. So that narrow zone is probably the least effective place for a bullet to end up, in a life or death situation.

Edit: BTW, this would still be considered a good hit by military standards, but not so much from a self-defense point of view.

As far as vertebre go, most shots are not going to be from behind, but rather frontal/side/oblique type shots. Specifically sniper engagement zones, but would work for most firearm engagements also.

There's very little soft tissue immediately in front of the spine, between the top of the sternum and the chin. And either side of that is the jugular veins and the carotid arteries. So a shot doesn't need to come from behind to be effective at hitting the spine, only fairly well centered.

Here's a cross section of the human neck. The front is at the top. As you can see, there's not a lot to slow down or deflect a bullet before it hits the spine.

So, a shot from the front is just as likely to have the desired result as from any other direction, where the vertebrae are concerned. And if it's a bit left or right, there's no bone to deflect the bullet away from the major arteries, as there is from the rear.

The bottom line is that the neck/throat area is a very good place to land a shot, from a "quick stop" standpoint.

J.

Edited July 27, 2010 by Jamie

[TNRobocop]

We are talking apples and oranges here.

The COM shots are for engagement purposes the largest area to place a round in a gunfight is the point I am trying to get across. Most hits to anywhere in this area will cause serious damage, physical and psychological.

The neck area is a very narrow engagement area for trying to place a shot, especially under stress and with a target that is probably in motion. In a perfect world with a target locked into a vise, your magic neck shot might work as intended. Lots of individuals have be shot in the neck or sustained shrapnel injuries in combat to the neck and throat area and survived.

If you want to talk technical go right on ahead. I am referring to real world training. Except for precision shooting, I would never emphasize anything other than COM.

Edited July 27, 2010 by TNRobocop

[Guest rsgillmd]

............Maybe not if it's a near-miss, but if a person is squarely hit through any one of the 1st through 7th vertebrae, they'll hit the ground like a sack of . And if the hit is higher than about C-4, they won't even be able to lift a finger, much less continue an attack.

They may or may not die from the wound, but you can't get much more stopped than they'll be, short of dying. And it's possible that even a glancing blow on that portion of the spine may have that effect.

J.

Totally agree with you, although you would be unlikely to hit above C4 unless you come from the side. Your hyoid bone is generally located about C2. Your thyroid cartilage is generally located about C4. Your cricoid cartilage is generally located about C6. The chin in an average person usually comes down to C3-C4.

[Guest Jamie]

We are talking apples and oranges here.

The COM shots are for engagement purposes the largest area to place a round in a gunfight is the point I am trying to get across.

And I'm talking about planting a round in the middle of the largest effective area.

A bullet that passes through a non-vital area isn't going to be very useful, no matter how large that is. So shooting an armed fat man squarely in the middle of his big ol' belly isn't nearly as likely to keep him from shooting YOU as taping him between his nipples or in the hollow of his throat.

The neck area is a very narrow engagement area for trying to place a shot, especially under stress and with a target that is probably in motion. In a perfect world with a target locked into a vise, your magic neck shot might work as intended.

Well, there's nothing magic about it, but the point is that it'll work a helluva lot better than passing a round under his kidney will be. By adjusting your point of aim a little bit higher, a low shot still ends up hitting something important, and also give the high ones just as much of a chance as they had when you were aiming a little lower.

Seems like a win to me.

If you want to talk technical go right on ahead. I tend to talk real world.

Robo, I started my first martial arts class when you were about 5 years old... and joined the U.S. Army when you were only about 9 or so... and joined the local sheriff's office about 17 years after that. So believe me when I tell you I am talking "real world applications" here, not just a load of crap out of a textbook.

J.

[eapking]

Check out the Dirty Harry movie "Magnum Force" sometime. Pay close attention to the scene where Harry is practice shooting on an indoor range with the 3 bad rookie cops. The target they use is a bit like the HCP Qualifying target we know well, except that the square area in the chest is not present. Instead there is a circle in the lower abdomen area. I've always found that interesting. Back in '74 somebody must have had a different theory than today, at least in San Francisco.

[TNRobocop]

Jaime you have a whole 7 years and change on me. Big deal.

I went in the army at 17, and have served in various branches since then for around 22 years. Worked LE since 1997.

I would think that my experience is roughly the same as yours.

Yes you are right that in a perfect world your hits would work. We don't work or live in a perfect world and with the average firearms skill proficiency level of most individuals, civilian, LE, or Military, it is unrealistic to espouse hits to those areas.

People rarely rise to the occassion, they default to their level of training.

[Guest Jamie]

One of the things that I hope people reading this thread will understand is that in a self-defense situation, the parts you need to put holes in aren't something you can see when you aim the gun. They are all hidden underneath what's presented to you. So to simply say "aim for center mass" is more than a little misleading.

A person really needs to have a working knowledge of basic human anatomy, and be able to shoot at a core area inside a container that doesn't let them see their target. Sort of like trying to hit an orange that's suspended inside a shoe box: You have to know where it is in order to make a hole in it... or just shoot until you do and let luck handle the rest.

Granted, luck is going to play a part in it anyway, given some of the crazy things even the best-aimed bullets can do once they hit something. But even for that, you can improve your odds considerably simply by knowing where organs are located, and being able to think in three dimensions, rather than just looking for a particular surface landmark and depending on that.

"Gut shots" with handgun calibers by and large aren't going to stop a person very quickly. Neither are most shots that land on the thighs or upper arms. Even pelvic shots are dicey, since you have to hit either the joint it's self, or a major artery.

The face is generally off limits too, unless you use the natural pathways to the brain... eye sockets, the nasal cavity, or an open mouth. All tough targets to hit, but they offer the least resistance to an underpowered projectile. ( The human skull is very thin in the front, behind the facial bones. Thin enough to be translucent in places. )

Anyway, the whole point of this post, if there is one, is to let folks know that one of the most useful things they can do is to find either a good anatomy book, or hunt down the Gray's Anatomy site, and study up a bit on where all the important bits and pieces of the human body are, and think about getting a bullet to them from any angle a person is apt to present, and what's apt to be in the way from any given angle. ( Like maybe an upper arm bone, on a quartering or lateral shot, that could deflect your bullet. )

J.

[Guest Boogieman]

Belly button to the top of the sternum. I had that worked out before reading all of the above. It's like hunting where you aim for the vitals. We know where our own vitals are and should aim accordingly. Unless its all out Men In Black style and we're dealing with Ballchininans.Then there might be some issues.

[Guest Jamie]

Jaime you have a whole 7 years and change on me. Big deal.

8 actually, and I feel every damned minute of 'em.

I went in the army at 17, and have served in various branches since then for around 22 years. Worked LE since 1997.

The military training is glaringly obvious. The LE.... not so much.

I would think that my experience is roughly the same as yours.

And you'd be wrong; I had sense enough to not spend anywhere near that long in the military. I have far more experience in civilian areas of self defense and shooting than military, as well as the hand-to-hand and anatomical stuff I mentioned earlier. ( You want to learn how to take something apart, you really need to know how it's put together. )

Yes you are right that in a perfect world your hits would work. We don't work or live in a perfect world and with the average firearms skill proficiency level of most individuals, civilian, LE, or Military, it is unrealistic to espouse hits to those areas.

Pay attention here, 'cause I'm getting really tired of this crap: I haven't been talking about a "prefect world" or a "perfect shot". I've been talking about increasing the chances that a missed shot will still be instantly incapacitating.

If a person starts off aiming too low to begin with, then further pulls his/her shot even lower, it'll be less effective given what you are advocating than what I've mentioned.

We're not talking about trying to make an eye shot on a running target from 50 yards here, only where the best place to try to hit is, in regards to near misses and groups opening up to 3 or 4 times what a person can do on the range.

People rarely rise to the occassion, they default to their level of training.

Yes, and that's all the more reason for them to train properly, no?

I don't know if you're aware of it or not, but several defensive handgun instructors now advocate aiming at the center of a triangle that's made by drawing a line from a person's nose, to one nipple, then the other, then back to their nose. I forget what term has been applied to it, and although it seems a bit high to me, I have to admit that any shot that lands inside that area is likely to be very good at shutting the person down.

I can also tell you that all of the targets we used at the S.O. for qualifications had the "center mass" where I've mentioned ( centered over the tip of the sternum, or xiphoid process ), with the area of the spine in both directions highlighted and counted higher as well. And I don't remember anybody ever mentioning that the spinal hits would only count if fired into the rear of the target.

Anyway, as to the OP and the original question, the term "center mass" has pretty much meant the center of a group of organs more so than any overall center of the human body, or even the human torso, in most of the training I've had. ( The military being the exception. ) And that being the case, it's probably outdated, and simply carried over from the days when a soldier was told to aim for the enemy's belt buckle.

When it comes right down to it, I guess it doesn't really matter much where a person is aiming, so long as they get the job done and the threat stopped.

J.

[Guest Jamie]

Missed this one earlier...

Totally agree with you, although you would be unlikely to hit above C4 unless you come from the side. Your hyoid bone is generally located about C2. Your thyroid cartilage is generally located about C4. Your cricoid cartilage is generally located about C6. The chin in an average person usually comes down to C3-C4.

If you're shooting straight at their face or if they have their head down, yeah. But if you're on the ground and shooting at a standing person, or even if you've fired with the gun held low, as with some types of point or instinctive shooting, the shot could come up under their chin at an angle and get there. ( Remember, we're talking about "missed" shots here, that don't go where they were intended. )

Then again, maybe you'll be attacked by someone with a very large, open mouth.

J.

[Fallguy]

Guess I've always taken COM to mean any where below the neck and above the belt, while primarily meaning/aiming for around the sternum.

I also thought it was a term used more just to mean don't aim for the limbs or head, since those would be smaller targets. You sometimes hear why didn't he just shoot him in the leg or arm. (To make him stop coming toward you or drop the weapon) ...and I assume head shots were/are discouraged because in the rush of the situation it would be a hard target to hit.

But my experience/education is no where near those that have heavily debated this already....but I just wanted to be included...

[Guest Jamie]

But my experience/education is no where near those that have heavily debated this already....

It really doesn't take a lot of training or knowledge. A quick look through almost any anatomy book or web site, and a little common sense, will pretty much tell a person where they want to make the holes, and where the best spot is to try and center their groups.

A little more thinking about where all that stuff is - and how to get to it - from different angles, and you're all set.

...but I just wanted to be included...

We certainly wouldn't want ya to feel left out.

J.